Place your phone into the recessed slot in the Boomerang, Charger then slide across the protective cover. Now repeatedly throw and catch your boomerang to charge it up. This is possible because contained within the body of the boomerang is a converter that transfers the rotational motion force to that of electrical energy, then delivers this to the phone. The boomerang itself has extra weighted tips to further increase its momentum.
A large number of throws may be required in order to make a short call or send a text message. "You rang?"-- xenzag, Sep 04 2015 Something easier Things_20with_20StringsA notion that is a bit more direct, at getting energy into the phone. [Vernon, Sep 04 2015] How about a yo-yo? Or a powerball?-- MaxwellBuchanan, Sep 04 2015 They're ok, but the 'rang' of boomerang is hard to resist when it comes to phones, plus I like the idea of using a 20,000 year old technology as an emergency solution to a 21st century device.-- xenzag, Sep 04 2015 Wait. If you're converting the rotational kinetic energy into electrical energy, then there's not enough boom left in your rang ... so, basically, you're just throwing a stick.
This is fine, provided that your dog will bring it back. In that case, though, you'd do better to charge your phone from the piezoelectric crystals in the handle of your extensible dog leash.
"Ooh, is that a wood pigeon?" might get you 100 Newtons sustained for, say, 5 seconds, before he realizes there's no wood pigeon. Is that really 10kj before conversion losses? That seems rather high.-- pertinax, Sep 09 2015 random, halfbakery